Subscribers of packet network services, e.g., VoIP network services are increasingly using premise based Network Address Translation (NAT) devices, such as a NAT router, to allow them to share a single public IP address among multiple networked devices. In addition to mapping multiple private IP addresses into a single public IP address, these NAT devices protect premise-based equipment from public attacks from the Internet by blocking uninitiated communication requests to the subscriber from the public Internet. Unfortunately this extra layer of security sometimes prevents subscribers using these NAT devices from receiving VoIP calls. NAT is a method that converts the IP address from a private address to a public address. This allows multiple end point devices to share a single public IP address. It also prevents access to these end point devices from the public Internet without special configurations. NAT is used in home networks and corporations to allow multiple PCs to access the internet via Digital Subscriber Loop (DSL) or Cable Modem.
Therefore, a need exists for a method and apparatus for enabling the receipt of phone calls behind Network Address Translation devices in a packet network, e.g., a VoIP network.